code: def merged_shapes(nybb_polydf):
      # Merged geometry
      manhattan_bronx = nybb_polydf.loc[3:4]
      others = nybb_polydf.loc[0:2]
  
      collapsed = [
          others.geometry.union_all(),
          manhattan_bronx.geometry.union_all(),
      ]
      merged_shapes = GeoDataFrame(
          {"myshapes": collapsed},
          geometry="myshapes",
          index=pd.Index([5, 6], name="manhattan_bronx"),
          crs=nybb_polydf.crs,
      )
  
      return merged_shapes
  
imports: import warnings
  import numpy
  import pandas
  import geopandas
  from geopandas import GeoDataFrame, read_file
  from pandas.testing import assert_frame_equal
  import pytest
  from geopandas._compat import PANDAS_GE_15, PANDAS_GE_20
  from geopandas.testing import assert_geodataframe_equal, geom_almost_equals
label_desc: Use image node_id 2 for calling a global function with example usage: merged_shapes(nybb_polydf) and returns: merged_shapes